Purpose: :
Computer vision syndrome (CVS) is a complex of eye and visionproblems experienced during or related to computer use. Ocularsymptoms may include asthenopia, accommodative and vergencedifficulties and dry eye. CVS occurs in up to 90% of computerworkers, and given the almost universal use of these devices,it is important to identify whether these symptoms are specificto computer operation, or are simply a manifestation of performinga sustained near-vision task.

Methods: :
This study compared ocular and non-ocular symptoms immediatelyfollowing a sustained near task. 30 young, visually-normal subjectsread text aloud either from a desktop computer screen or a printedhardcopy page at a viewing distance of 50cm for a continuous20 min period. Identical text was used in the two sessions,which was matched for size and contrast. Additionally, targetviewing angle and luminance were similar for the two conditions.Immediately following completion of the reading assignment,subjects completed a written questionnaire relating to theirlevel of ocular and general discomfort during the task.

Results: :
Symptoms were reported on a scale from 1 (very mild) to 10 (verysevere). When comparing the computer and hardcopy conditions,significant differences in mean ocular symptom scores were reportedwith regard to blurred vision during the task (3.53 v 2.28;p=0.006) and dry eye (3.33 v 2.43; p=0.05). In both cases, symptomswere higher during computer use. However, no significant differenceswere observed between the two tasks in relation to blurred distancevision after nearwork, focusing difficulties, eyestrain, headache,light sensitivity or the eyes feeling irritated, uncomfortableor tired. Additionally, significant differences in non-ocularsymptoms relating to discomfort in the elbow, hand/wrist andfingers were also observed, with the computer condition beingworse in all these categories.

Conclusions: :
Symptoms following sustained computer use are significantlyworse than those reported after hard copy fixation under similarviewing conditions. A better understanding of the physiologyunderlying CVS is critical to allow more accurate diagnosisand treatment. This will enable practitioners to optimize patient'svisual comfort and efficiency during computer operation.